1. Field of the Invention
The invention relates to a novel method of obtaining homopolymers and/or copolymers, in an aqueous solution of monoethylenically unsaturated monomers such as acrylic and/or vinyl monomers, making it possible to obtain directly usable polymers.
The invention also relates to the homopolymers and/or copolymers obtained by the said method as well as their use as an aid to the grinding and/or dispersion in aqueous solution of mineral materials, or as a sequestring agent or mineral scale and/or incrustation inhibitor in particular on the heat transfer surfaces of industrial or domestic installations or as a fluidising agent for aqueous solutions based on soft or saline water normally used as drilling fluids in the fields of civil engineering, building, public works, petroleum prospecting or extraction or as a zeolite suspension stabiliser and as an antiscaling agent or as a water retaining agent in the paper making industry or also as builder or co-builder in detergent compositions or finally as dispersant which does not destabilise the chlorometric rate of the hypochlorite compositions in the detergent formulations containing it.
Finally, the invention relates to the said aqueous solutions of mineral materials which are stable over time and have a high concentration of mineral materials as well as their use in the field of paper, paint, detergent and cleaning formulations and any other field using the said suspensions such as in particular ceramics or drilling fluids.
2. Discussion of the Background
For a long time already persons skilled in the art have known various methods for homopolymerising in solution acrylic and/or vinyl monomers such as in particular acrylic acid, methacrylic acid, maleic anhydride or acrylamide as well as for copolymerising, in solution in water, acrylic acid with other monoethylenically unsaturated monomers such as for example maleic anhydride, itaconic acid, acrylamide or acrylamido methyl propanesulfonic acid.
Thus the patents FR 2 751 335, EP 0 405 818, EP 0 618 240, U.S. Pat. No. 4,621,127 and EP 0 792 890 describe methods of polymerising acrylic acid.
Likewise a person skilled in the art has available U.S. Pat. No. 4,301,266, which describes a method of manufacturing acrylic acid polymers having the drawback of requiring the use of a solvent of the isopropanol type and requiring work under pressure, and distillation in order to eliminate the solvent.
Finally, persons skilled in the art also know the patents FR 2 539 137, EP 0 542 644 or EP 0 516 656 teaching that neutralisation of acrylic polymers with alkaline earths makes it possible to obtain agents for the grinding of calcium carbonate by the wet method, these suspensions being particularly stable over time.
However, all these polymerisation techniques well known to persons skilled in the art require a step of neutralisation of the polymer solution obtained in acid form or partially neutralised subsequently to the polymerisation reaction, then obliging the producer of these polymers either to equip himself with equipment specific to the polymerisation and another type of equipment peculiar to the neutralisation reactions or to occupy the polymerisation reactors for a longer time, which has the consequence of reducing the productivity of the installation and therefore increasing the cost of the products.